Analyses of rainfall extremes in East Africa based on observations from rain gauges and climate change simulations by CORDEX RCMs

2020 ◽  
Vol 54 (11-12) ◽  
pp. 4841-4864 ◽  
Author(s):  
Charles Onyutha
Keyword(s):  
Climate Change ◽  
East Africa ◽  
Rain Gauges ◽  
Rainfall Extremes

scholarly journals Epidemic malaria and warmer temperatures in recent decades in an East African highland

2010 ◽  
Vol 278 (1712) ◽  
pp. 1661-1669 ◽  
Author(s):  
David Alonso ◽  
Menno J. Bouma ◽  
Mercedes Pascual
Keyword(s):  
Climate Change ◽  
East Africa ◽  
Nonlinear Response ◽  
Climate Change Impacts ◽  
Human Model ◽  
Recent Past ◽  
East African ◽  
Highly Nonlinear ◽  
The Impact

Climate change impacts on malaria are typically assessed with scenarios for the long-term future. Here we focus instead on the recent past (1970–2003) to address whether warmer temperatures have already increased the incidence of malaria in a highland region of East Africa. Our analyses rely on a new coupled mosquito–human model of malaria, which we use to compare projected disease levels with and without the observed temperature trend. Predicted malaria cases exhibit a highly nonlinear response to warming, with a significant increase from the 1970s to the 1990s, although typical epidemic sizes are below those observed. These findings suggest that climate change has already played an important role in the exacerbation of malaria in this region. As the observed changes in malaria are even larger than those predicted by our model, other factors previously suggested to explain all of the increase in malaria may be enhancing the impact of climate change.

The effect of climate change on urban drainage: an evaluation based on regional climate model simulations

2006 ◽  
Vol 54 (6-7) ◽  
pp. 9-15 ◽  
Author(s):  
M. Grum ◽  
A.T. Jørgensen ◽  
R.M. Johansen ◽  
J.J. Linde
Keyword(s):  
Climate Change ◽  
Extreme Precipitation ◽  
Climate Model ◽  
Regional Climate ◽  
Rain Gauge ◽  
Urban Drainage ◽  
Extreme Precipitation Events ◽  
Rainfall Extremes ◽  
The Future ◽  
Precipitation Events

That we are in a period of extraordinary rates of climate change is today evident. These climate changes are likely to impact local weather conditions with direct impacts on precipitation patterns and urban drainage. In recent years several studies have focused on revealing the nature, extent and consequences of climate change on urban drainage and urban runoff pollution issues. This study uses predictions from a regional climate model to look at the effects of climate change on extreme precipitation events. Results are presented in terms of point rainfall extremes. The analysis involves three steps: Firstly, hourly rainfall intensities from 16 point rain gauges are averaged to create a rain gauge equivalent intensity for a 25 × 25 km square corresponding to one grid cell in the climate model. Secondly, the differences between present and future in the climate model is used to project the hourly extreme statistics of the rain gauge surface into the future. Thirdly, the future extremes of the square surface area are downscaled to give point rainfall extremes of the future. The results and conclusions rely heavily on the regional model's suitability in describing extremes at time-scales relevant to urban drainage. However, in spite of these uncertainties, and others raised in the discussion, the tendency is clear: extreme precipitation events effecting urban drainage and causing flooding will become more frequent as a result of climate change.

scholarly journals IMPACT OF CLIMATE CHANGE ON THE HYDRAULIC MODES OF OPERATION OF SURFACE RUNOFF DRAINAGE SYSTEMS

2020 ◽  
Vol 25 (4) ◽  
pp. 50-57
Author(s):  
V. S. Ignatchik ◽  
◽  
S. Y. Ignatchik ◽  
N. V. Kuznetsova ◽  
A. Y. Fes’kova ◽  
...  
Keyword(s):  
Climate Change ◽  
Linear Approximation ◽  
Surface Runoff ◽  
Annual Precipitation ◽  
Climatic Parameters ◽  
Modes Of Operation ◽  
Total Annual Precipitation ◽  
Rain Gauges ◽  
Drainage Networks ◽  
The Government

Introduction. Based on Resolution of the Government of the Russian Federation No. 782 “On water supply and wastewater disposal plans”, the volume of generated wastewater should be forecast for a period of at least 10 years. Along with this, it is also necessary to assess the hydraulic modes of operation of networks and collectors, specified earlier. However, the existing regulatory literature lacks data on the dynamics of calculated rain intensities and their prospective values. The analysis of the subject area showed that it is possible to determine the climatic parameters of an area, and thus establish the values for the characteristics of calculated rain, based on the data of long-term observations (from 20 years) with one self-recording rain gauge, or with a network of similar rain gauges, with a duration of observations of 5 years or more. A similar network of rain gauges is available in St. Petersburg. It makes it possible to assess the actual values of climatic parameters, but due to the lack of statistical data does not allow for assessing the dynamics of their changes. Therefore, the purpose of this article is to roughly estimate the dynamics of changes in climatic parameters in St. Petersburg and the degree of their impact on the hydraulic modes of operation of surface runoff drainage networks and collectors. Methods. In the course of the study, we analyzed the dynamics of changes in the total annual precipitation H and rain force in St. Petersburg and examined the influence of the dynamics of rain force changes on the operation of surface runoff drainage networks and collectors. Results. At the first stage of the study, we obtained the results of linear approximation of the H data, the calculated values of rain force changes Δ, and the results of linear approximation of the Δ data. The second stage of the study resulted in changes in the hydraulic modes of runoff input during the design period and in 50 years. Conclusion. We experimentally substantiated the possibility to determine the dynamics of rain force changes (at P = 0.33 and with acceptable accuracy) depending on the dynamics of changes in the total annual precipitation. For networks designed and laid 50 years ago, the actual rain force changes will be 9 %. As a result of climate change, water consumption in the calculation periods increased by about 26% with an increase in the total volume of discharged water by 9–10 %.

scholarly journals At-site and regional frequency analysis of extreme precipitation from radar-based estimates

2017 ◽  
Author(s):  
Edouard Goudenhoofdt ◽  
Laurent Delobbe ◽  
Patrick Willems
Keyword(s):  
Confidence Interval ◽  
Frequency Analysis ◽  
Extreme Precipitation ◽  
Rain Gauge ◽  
Regional Frequency Analysis ◽  
Extreme Value Analysis ◽  
Value Analysis ◽  
Rain Gauges ◽  
Rainfall Extremes ◽  
Regional Frequency

Abstract. In Belgium, only rain gauge time-series have been used so far to study extreme precipitation at a given location. In this paper, the potential of a 12-year quantitative precipitation estimation (QPE) from a single weather radar is evaluated. For the period 2005–2016, independent sliding 1 h and 24 h rainfall extremes from automatic rain gauges and collocated radar estimates are compared. The extremes are fitted to the exponential distribution using regression in QQ-plots with a threshold rank which minimises the mean squared error. A basic radar product used as reference exhibits unrealistic high extremes and is not suitable for extreme value analysis. For 24 h rainfall extremes, which occur partly in winter, the radar-based QPE needs a bias correction. A few missing events are caused by the wind drift of convective cells and strong radar signal attenuation. Differences between radar and gauge values are caused by spatial and temporal sampling, gauge rainfall underestimations and radar errors due to the relation between reflectivity and rain rate. Nonetheless the fit to the QPE data is within the confidence interval of the gauge fit, which remains large due to the short study period. A regional frequency analysis is performed on radar data within 20 km of the locations of 4 rain gauges with records from 1965 to 2008. Assuming that the extremes are correlated within the region, the fit to the two closest rain gauge data is within the confidence interval of the radar fit, which is small due to the sample size. In Brussels, the extremes on the period 1965–2008 from a rain gauge are significantly lower than the extremes from an automatic gauge and the radar on the period 2005–2016. For 1 h duration, the location parameter varies slightly with topography and the scale parameter exhibits some variations from region to region. The radar-based extreme value analysis can be extended to other durations.

scholarly journals Precipitation over southern Africa: Is there consensus among GCMs, RCMs and observational data?

2021 ◽  
Author(s):  
Maria Chara Karypidou ◽  
Eleni Katragkou ◽  
Stefan Pieter Sobolowski
Keyword(s):  
Climate Change ◽  
Southern Africa ◽  
Regional Climate ◽  
Coupled Model ◽  
Added Value ◽  
Rain Gauges ◽  
Climate Simulations ◽  
Observational Uncertainty ◽  
Direct Contrast ◽  
Improved Performance

Abstract. The region of southern Africa (SAF) is highly vulnerable to the impacts of climate change and is projected to experience severe precipitation shortages in the coming decades. Ensuring that our modelling tools are fit for the purpose of assessing these changes is critical. In this work we compare a range of satellite products along with gauge-based datasets. Additionally, we investigate the behaviour of regional climate simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX) – Africa domain, along with simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) and Phase 6 (CMIP6). We identify considerable variability in the standard deviation of precipitation between satellite products that merge with rain gauges and satellite products that do not, during the rainy season (Oct–Mar), indicating high observational uncertainty for specific regions over SAF. Good agreement both in spatial pattern and the strength of the calculated trends is found between satellite and gauge-based products, however. Both CORDEX-Africa and CMIP5 ensembles underestimate the observed trends during the analysis period. The CMIP6 ensemble displayed persistent drying trends, in direct contrast to the observations. The regional ensemble exhibited improved performance compared to its forcing (CMIP5), when the annual cycle and the extreme precipitation indices were examined, confirming the added value of the higher resolution regional climate simulations. The CMIP6 ensemble displayed a similar behaviour to CMIP5, however reducing slightly the ensemble spread. However, we show that reproduction of some key SAF phenomena, like the Angolan Low (which exerts a strong influence on regional precipitation), still poses a challenge for the global and regional models. This is likely a result of the complex climatic process that take place. Improvements in observational networks (both in-situ and satellite), as well as continued advancements in high-resolution modelling will be critical, in order to develop a robust assessment of climate change for southern Africa.

scholarly journals Extreme rainfall in East Africa, October 2019–January 2020 and context under future climate change

Weather ◽  
2020 ◽  
Author(s):  
Caroline M. Wainwright ◽  
Declan L. Finney ◽  
Mary Kilavi ◽  
Emily Black ◽  
John H. Marsham
Keyword(s):  
Climate Change ◽  
East Africa ◽  
Extreme Rainfall ◽  
Future Climate ◽  
Future Climate Change

Climate Change and People Change: Dancing the Dialectic

2017 ◽  
Vol 10 (2) ◽  
pp. 72-81
Author(s):  
Paul O'Keefe
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
East Africa ◽  
Livelihood Strategies ◽  
Extreme Conditions ◽  
Intergovernmental Panel ◽  
Human Environment ◽  
Assessment Report ◽  
Dialectical Approach ◽  
The Subject

The fifth assessment report of the Intergovernmental Panel on Climate Change (IPCC, 2014) says that accelerated climate change is occurring because of enhanced release of greenhouse gases. It is projected that temperatures will increase in East Africa but there is no agreement on how precipitation will change. There is acceptance that the climate system will throw up more frequent extreme conditions, including drought. We can begin to understand how this will materialize in people's livelihood strategies and adaptive choices. This paper identifies theoretical problems in the dominant discourses surrounding human-environment relations and climate change, and argues for a dialectical approach to the subject. It concludes with a brief vignette focused on a dialectical study of climate change.

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